Dust-cap



H. P. KRAFT.

nus CAP.l

APPLICATION FILED MAYZ. |919,

Patented Sept. 9, 1919.

` INVENTOR l? @@W 1 I I lll d WITNESS f/ By Attorneys,

STATEeIFENT Dusar-cai.

lcap is to inclose the projecting end of the 4valve of a pneumatic tire for the purpose of excluding dust, mud, etc., and ior the purpose of protecting the valve and its cap .from shocks or blows, caused by impact with stones or .other objects.

',.Ori inally such caps were formed of solid metal ored to cap form and provided with a thread adapted to engage. the threads oi' the valve casing. Subsequently they were constructed by drawing deep cups irom sheet metal, the open end being contracted and threaded. By this means, the cost of construction was reduced by eliminating waste ofmetal and long boring and thread- `ing operations.V y Such drawn metal caps have been the standard construction for many years. While such caps show considerableeconomies over the older type of solid cap, they arenevertheless expensive to manufacture, duel` principally to the long series -1 bolf drawing operations.

.According to the present invention I providea dust cap which is eiiicient in operation, symmetrical in appearance, and exceedingly cheap in cost of construction. By the invention, such drawing operations may be :entirely eliminated, thus avoiding the principal ycauseof expense of the standard construction.` The' invention also enables the :full ladvantage to be taken of iron or steel'as a construction material, which, up to thev present, has not been availed of, due to the diiiculty of drawing the metal as Vcompared withbrass. It has been foundin `practice that `because of the lesser ductility of steel, the drawing operations have been much slower and the wear and tear on the dies'has been excessive.

i Specification of Letters Patent.

Applicaton'iiled May 2, 1919.

Serial No. 294,265.

Patented Sept. 9, 1919i My invention comprises essentially a dust cap formed in longitudinal sections, preferably two in number, which sections are preferably stamped up by a single blow of a stamping press, which not only produces the proper seinicylindricalshape, but also trims the blank, leaving but the operation ot' assembling to produce the complete unthreaded cap. Preferably such sections are united by flanges turned one over the other and preferably also each blank is provided with a rib extending longitudinally of the blank, andI spaced midway betweenl the` lianges, which rib extends outwardly as a substantial counterpart oi3 the flanges. so that the completed cap presents the exterior appearance of a closed cylinder liavingffour external ribs. Instead of being detrimental, these ribs serve the very .useful purpose of, providing a secure hand-hold (or tool-holdlm by means 0i which the ca may be easily manipulated. Both the anges and ribs serve as stidening members to enable the use of much thinner metal.l The invention also-includes, in its preferred form, a novel construction of threads arranged between the ribs, which will be hereinafter more fully described.

Referring to the drawings, which illustrate several forms or' the invention,--

Figure 1 is an elevation of a completed Cap;

Fig. 2 is a diametrical section of Fig. 1 on an enlarged scale;

Fig. 3 is a similar section taken at right angles to Fig. 2.

Fig. 4: is a cross-sectionl on the line 4.-'-4 in Fig. 2.

Fig. 5 is a cross-section on the line 5-5 vention includes means for permanently u`n1ting the sections preferably with a substantially leak-tight joint. This permanent union may be accomplished in several ways, but that preferred 1s by turning a flange on one section over a complementary flange on the other section.l This flange preferably extends 'entirely around the closed end of the cap and down the sides of the latter to the end,'as indicated at E in Fig. 1. Preferably one Vof thesections, as for instance C, is formed` with a wide flange F, and the other section, as B, with anarrow flange Gr4 adapted to abut theflange F, the latter then being Aturned over the top of the flange G, as best shown in Figs. 3 and 4, the inn turned portion being indicated by the letter H.

The flange E constitutes an efficient finger or tool hold in manipulating the cap. It also constitutes a very efficient stiifening member for imparting rigidity to the cap structure, thus permitting the use of lighter `metal than would otherwise be feasible.

Preferably I introduce into the structure, a plurality of deep ribs J, preferably arranged midway in the section between the sides of the flange E. These ribs extend outwardly and arearranged longitudinally of the cap, preferably being co-extensive with the sides of the flange E. Ordinarily they will be carried on their tops to points close to or meeting the flange. By properly proportioningv the flange and ribs very similar, if not identical, exterior form may be secured, so that the cap has the outward appearance ofa four-ribbed cap. This not only adds to the symmetrical apearance of the cap and providesadditional finger-hold, but also materially assists instiffening the cap.

In the process of constructing the shells or sections, a stamping press is preferably employed which is-adapted at one stroke to cut out a blank from a strip or sheet of metal, and to simultaneously form the ribs J.l

The flange F of the member C is of course wider than the flange G of the member B and may be cupped upwardly so that the lflange 'G will fit snugly within the flange F. The` two parts being assembled, the flange 'F'maybe turned down over the flange G by a si gle stroke of an appropriate press. In the'standard construction of cap, the

metal at the bottom or open end of the cap eis` pressed inwardly and interiorly screwthreaded by a suitable tap, the screw-threaded portion being of short length.

According to the present invention I prefer to form the threads by la pressing operation with simultaneously swages the metal inward and forms the threads. In carrying this into effect I provide a contracting arbor or die which is screw-threaded on its exterior and which is introduced into the open end of" the cap. Simultaneously four screw-threaded dies approachvfrom the exterior and engage the cap between theribs and flange, pressing the metal inwardly onto the arbor, thus not only contracting the foot of the cap but pressing the inet-al into the threads of the arbor. The arbor is then collapsed and Withdrawn by a longitudinal movement. During this same operation (or by anotheroperation) 'a liange K is preferably formed on the foot of the cap so as to provide a wider bearing surface than would be secured by the thickness of the .and other cross-sections, however, are intended to be covered by the claims.

While I have shown and described certain forms of the invention, it will be understood that I do not wish to be limited thereto, as various changes may be made therein without departing from the spirit of the invention.

1. A dust cap for tire valves or the like, comprising a plurality of longitudinal sec tions permanently and rigidly united to con stit'ute a unitary cap structure having a closed outer end and an open inner end, the cap having means for connection with a tire valve or the"like.

2. A dust cap for tire valves or the like, comprising a plurality of longitudinal sections permanently and rigidly united from end to end to constitute a unitary cap structure having a closed outer end and an open inner end, the cap having at its lower end thread-engaging means to adapt it for connection with a tire valve or the like.

3. A dust cap for tire valves or the like comprising a plurality of longitudinal sections permanently and rigidly united to constitute a unitary cap structure by interengaging flanges formed upon the sections and extending around the closed top of the cap.

l. A dust cap for tire valves or the like, comprising a plurality of longitudinal sections, the sections being permanently united to constitute a unitary cap structure by inter-engaging flanges formed upon the sections.

' 5. A dust cap for tire valves or the like comprising a plurality ofu longitudinal sections, the sections being `permanently united to constitute a unitary cap structure by outwerdly projecting interengaging flanges formed upon the sections.

6. A dust C21-p for tire vlves or the like, comprising e. plurality of iongitudnnl Seetions, the sections'being pernmnently united to constitute n unitary oep structure by a Wide flange formed on one section and e narrow Harige formed on. the other section, the Wide flange being turned over the nm'- 10 row zinge.

7. A dust cap for tire, valves or the like, comprising two longitudine] Aectio'ns, the sections being` pernmnently united to oonst'itute n unitary Cep st1'ucture,'o11e section having Wide flanges und the other narrow flanges, and the wide anbfes being turned over to embrace the narrow flanges.

In witness nhereof'I have hereunto signed HENRY P. KRAFT. 

